[linux-2.6-block.git] / drivers / base / devtmpfs.c

// SPDX-License-Identifier: GPL-2.0
/*
 * devtmpfs - kernel-maintained tmpfs-based /dev
 *
 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
 *
 * During bootup, before any driver core device is registered,
 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
 * device which requests a device node, will add a node in this
 * filesystem.
 * By default, all devices are named after the name of the device,
 * owned by root and have a default mode of 0600. Subsystems can
 * overwrite the default setting if needed.
 */

#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/namei.h>
#include <linux/fs.h>
#include <linux/shmem_fs.h>
#include <linux/ramfs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <uapi/linux/mount.h>
#include "base.h"

static struct task_struct *thread;

#if defined CONFIG_DEVTMPFS_MOUNT
static int mount_dev = 1;
#else
static int mount_dev;
#endif

static DEFINE_SPINLOCK(req_lock);

static struct req {
	struct req *next;
	struct completion done;
	int err;
	const char *name;
	umode_t mode;	/* 0 => delete */
	kuid_t uid;
	kgid_t gid;
	struct device *dev;
} *requests;

static int __init mount_param(char *str)
{
	mount_dev = simple_strtoul(str, NULL, 0);
	return 1;
}
__setup("devtmpfs.mount=", mount_param);

static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
		      const char *dev_name, void *data)
{
#ifdef CONFIG_TMPFS
	return mount_single(fs_type, flags, data, shmem_fill_super);
#else
	return mount_single(fs_type, flags, data, ramfs_fill_super);
#endif
}

static struct file_system_type dev_fs_type = {
	.name = "devtmpfs",
	.mount = dev_mount,
	.kill_sb = kill_litter_super,
};

#ifdef CONFIG_BLOCK
static inline int is_blockdev(struct device *dev)
{
	return dev->class == &block_class;
}
#else
static inline int is_blockdev(struct device *dev) { return 0; }
#endif

int devtmpfs_create_node(struct device *dev)
{
	const char *tmp = NULL;
	struct req req;

	if (!thread)
		return 0;

	req.mode = 0;
	req.uid = GLOBAL_ROOT_UID;
	req.gid = GLOBAL_ROOT_GID;
	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
	if (!req.name)
		return -ENOMEM;

	if (req.mode == 0)
		req.mode = 0600;
	if (is_blockdev(dev))
		req.mode |= S_IFBLK;
	else
		req.mode |= S_IFCHR;

	req.dev = dev;

	init_completion(&req.done);

	spin_lock(&req_lock);
	req.next = requests;
	requests = &req;
	spin_unlock(&req_lock);

	wake_up_process(thread);
	wait_for_completion(&req.done);

	kfree(tmp);

	return req.err;
}

int devtmpfs_delete_node(struct device *dev)
{
	const char *tmp = NULL;
	struct req req;

	if (!thread)
		return 0;

	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
	if (!req.name)
		return -ENOMEM;

	req.mode = 0;
	req.dev = dev;

	init_completion(&req.done);

	spin_lock(&req_lock);
	req.next = requests;
	requests = &req;
	spin_unlock(&req_lock);

	wake_up_process(thread);
	wait_for_completion(&req.done);

	kfree(tmp);
	return req.err;
}

static int dev_mkdir(const char *name, umode_t mode)
{
	struct dentry *dentry;
	struct path path;
	int err;

	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
	if (!err)
		/* mark as kernel-created inode */
		d_inode(dentry)->i_private = &thread;
	done_path_create(&path, dentry);
	return err;
}

static int create_path(const char *nodepath)
{
	char *path;
	char *s;
	int err = 0;

	/* parent directories do not exist, create them */
	path = kstrdup(nodepath, GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	s = path;
	for (;;) {
		s = strchr(s, '/');
		if (!s)
			break;
		s[0] = '\0';
		err = dev_mkdir(path, 0755);
		if (err && err != -EEXIST)
			break;
		s[0] = '/';
		s++;
	}
	kfree(path);
	return err;
}

static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
			 kgid_t gid, struct device *dev)
{
	struct dentry *dentry;
	struct path path;
	int err;

	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
	if (dentry == ERR_PTR(-ENOENT)) {
		create_path(nodename);
		dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
	}
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
	if (!err) {
		struct iattr newattrs;

		newattrs.ia_mode = mode;
		newattrs.ia_uid = uid;
		newattrs.ia_gid = gid;
		newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
		inode_lock(d_inode(dentry));
		notify_change(dentry, &newattrs, NULL);
		inode_unlock(d_inode(dentry));

		/* mark as kernel-created inode */
		d_inode(dentry)->i_private = &thread;
	}
	done_path_create(&path, dentry);
	return err;
}

static int dev_rmdir(const char *name)
{
	struct path parent;
	struct dentry *dentry;
	int err;

	dentry = kern_path_locked(name, &parent);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	if (d_really_is_positive(dentry)) {
		if (d_inode(dentry)->i_private == &thread)
			err = vfs_rmdir(d_inode(parent.dentry), dentry);
		else
			err = -EPERM;
	} else {
		err = -ENOENT;
	}
	dput(dentry);
	inode_unlock(d_inode(parent.dentry));
	path_put(&parent);
	return err;
}

static int delete_path(const char *nodepath)
{
	char *path;
	int err = 0;

	path = kstrdup(nodepath, GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	for (;;) {
		char *base;

		base = strrchr(path, '/');
		if (!base)
			break;
		base[0] = '\0';
		err = dev_rmdir(path);
		if (err)
			break;
	}

	kfree(path);
	return err;
}

static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
{
	/* did we create it */
	if (inode->i_private != &thread)
		return 0;

	/* does the dev_t match */
	if (is_blockdev(dev)) {
		if (!S_ISBLK(stat->mode))
			return 0;
	} else {
		if (!S_ISCHR(stat->mode))
			return 0;
	}
	if (stat->rdev != dev->devt)
		return 0;

	/* ours */
	return 1;
}

static int handle_remove(const char *nodename, struct device *dev)
{
	struct path parent;
	struct dentry *dentry;
	int deleted = 0;
	int err;

	dentry = kern_path_locked(nodename, &parent);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	if (d_really_is_positive(dentry)) {
		struct kstat stat;
		struct path p = {.mnt = parent.mnt, .dentry = dentry};
		err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
				  AT_STATX_SYNC_AS_STAT);
		if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
			struct iattr newattrs;
			/*
			 * before unlinking this node, reset permissions
			 * of possible references like hardlinks
			 */
			newattrs.ia_uid = GLOBAL_ROOT_UID;
			newattrs.ia_gid = GLOBAL_ROOT_GID;
			newattrs.ia_mode = stat.mode & ~0777;
			newattrs.ia_valid =
				ATTR_UID|ATTR_GID|ATTR_MODE;
			inode_lock(d_inode(dentry));
			notify_change(dentry, &newattrs, NULL);
			inode_unlock(d_inode(dentry));
			err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
			if (!err || err == -ENOENT)
				deleted = 1;
		}
	} else {
		err = -ENOENT;
	}
	dput(dentry);
	inode_unlock(d_inode(parent.dentry));

	path_put(&parent);
	if (deleted && strchr(nodename, '/'))
		delete_path(nodename);
	return err;
}

/*
 * If configured, or requested by the commandline, devtmpfs will be
 * auto-mounted after the kernel mounted the root filesystem.
 */
int devtmpfs_mount(const char *mntdir)
{
	int err;

	if (!mount_dev)
		return 0;

	if (!thread)
		return 0;

	err = ksys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT,
			 NULL);
	if (err)
		printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	else
		printk(KERN_INFO "devtmpfs: mounted\n");
	return err;
}

static DECLARE_COMPLETION(setup_done);

static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
		  struct device *dev)
{
	if (mode)
		return handle_create(name, mode, uid, gid, dev);
	else
		return handle_remove(name, dev);
}

static int devtmpfsd(void *p)
{
	char options[] = "mode=0755";
	int *err = p;
	*err = ksys_unshare(CLONE_NEWNS);
	if (*err)
		goto out;
	*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
	if (*err)
		goto out;
	ksys_chdir("/.."); /* will traverse into overmounted root */
	ksys_chroot(".");
	complete(&setup_done);
	while (1) {
		spin_lock(&req_lock);
		while (requests) {
			struct req *req = requests;
			requests = NULL;
			spin_unlock(&req_lock);
			while (req) {
				struct req *next = req->next;
				req->err = handle(req->name, req->mode,
						  req->uid, req->gid, req->dev);
				complete(&req->done);
				req = next;
			}
			spin_lock(&req_lock);
		}
		__set_current_state(TASK_INTERRUPTIBLE);
		spin_unlock(&req_lock);
		schedule();
	}
	return 0;
out:
	complete(&setup_done);
	return *err;
}

/*
 * Create devtmpfs instance, driver-core devices will add their device
 * nodes here.
 */
int __init devtmpfs_init(void)
{
	int err = register_filesystem(&dev_fs_type);
	if (err) {
		printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
		       "type %i\n", err);
		return err;
	}

	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	if (!IS_ERR(thread)) {
		wait_for_completion(&setup_done);
	} else {
		err = PTR_ERR(thread);
		thread = NULL;
	}

	if (err) {
		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
		unregister_filesystem(&dev_fs_type);
		return err;
	}

	printk(KERN_INFO "devtmpfs: initialized\n");
	return 0;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
2b2af54a KS	2	/*
	3	* devtmpfs - kernel-maintained tmpfs-based /dev
	4	*
	5	* Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
	6	*
	7	* During bootup, before any driver core device is registered,
	8	* devtmpfs, a tmpfs-based filesystem is created. Every driver-core
	9	* device which requests a device node, will add a node in this
e454cea2	10	* filesystem.
02fbe5e6 PK	11	* By default, all devices are named after the name of the device,
	12	* owned by root and have a default mode of 0600. Subsystems can
	13	* overwrite the default setting if needed.
2b2af54a KS	14	*/
	15
	16	#include <linux/kernel.h>
	17	#include <linux/syscalls.h>
	18	#include <linux/mount.h>
	19	#include <linux/device.h>
	20	#include <linux/genhd.h>
	21	#include <linux/namei.h>
	22	#include <linux/fs.h>
	23	#include <linux/shmem_fs.h>
da5e4ef7	24	#include <linux/ramfs.h>
e454cea2	25	#include <linux/sched.h>
5a0e3ad6	26	#include <linux/slab.h>
2780f1ff	27	#include <linux/kthread.h>
e262e32d	28	#include <uapi/linux/mount.h>
c3a30420	29	#include "base.h"
2b2af54a	30
2780f1ff	31	static struct task_struct *thread;
2b2af54a KS	32
2b2af54a KS	33	#if defined CONFIG_DEVTMPFS_MOUNT
fc14f2fe	34	static int mount_dev = 1;
2b2af54a	35	#else
fc14f2fe	36	static int mount_dev;
2b2af54a KS	37	#endif
2b2af54a KS	38
2780f1ff AV	39	static DEFINE_SPINLOCK(req_lock);
	40
	41	static struct req {
	42	struct req *next;
	43	struct completion done;
	44	int err;
	45	const char *name;
2c9ede55	46	umode_t mode; /* 0 => delete */
4e4098a3 GKH	47	kuid_t uid;
4e4098a3 GKH	48	kgid_t gid;
2780f1ff AV	49	struct device *dev;
2780f1ff AV	50	} *requests;
ed413ae6	51
2b2af54a KS	52	static int __init mount_param(char *str)
2b2af54a KS	53	{
fc14f2fe	54	mount_dev = simple_strtoul(str, NULL, 0);
2b2af54a KS	55	return 1;
	56	}
	57	__setup("devtmpfs.mount=", mount_param);
	58
fc14f2fe AV	59	static struct dentry dev_mount(struct file_system_type fs_type, int flags,
fc14f2fe AV	60	const char dev_name, void data)
2b2af54a	61	{
da5e4ef7	62	#ifdef CONFIG_TMPFS
fc14f2fe	63	return mount_single(fs_type, flags, data, shmem_fill_super);
da5e4ef7	64	#else
fc14f2fe	65	return mount_single(fs_type, flags, data, ramfs_fill_super);
da5e4ef7	66	#endif
2b2af54a KS	67	}
	68
	69	static struct file_system_type dev_fs_type = {
	70	.name = "devtmpfs",
fc14f2fe	71	.mount = dev_mount,
2b2af54a KS	72	.kill_sb = kill_litter_super,
	73	};
	74
	75	#ifdef CONFIG_BLOCK
	76	static inline int is_blockdev(struct device *dev)
	77	{
	78	return dev->class == &block_class;
	79	}
	80	#else
	81	static inline int is_blockdev(struct device *dev) { return 0; }
	82	#endif
	83
2780f1ff AV	84	int devtmpfs_create_node(struct device *dev)
	85	{
	86	const char *tmp = NULL;
	87	struct req req;
	88
	89	if (!thread)
	90	return 0;
	91
	92	req.mode = 0;
4e4098a3 GKH	93	req.uid = GLOBAL_ROOT_UID;
4e4098a3 GKH	94	req.gid = GLOBAL_ROOT_GID;
3c2670e6	95	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
2780f1ff AV	96	if (!req.name)
	97	return -ENOMEM;
	98
	99	if (req.mode == 0)
	100	req.mode = 0600;
	101	if (is_blockdev(dev))
	102	req.mode \|= S_IFBLK;
	103	else
	104	req.mode \|= S_IFCHR;
	105
	106	req.dev = dev;
	107
	108	init_completion(&req.done);
	109
	110	spin_lock(&req_lock);
	111	req.next = requests;
	112	requests = &req;
	113	spin_unlock(&req_lock);
	114
	115	wake_up_process(thread);
	116	wait_for_completion(&req.done);
	117
	118	kfree(tmp);
	119
	120	return req.err;
	121	}
	122
	123	int devtmpfs_delete_node(struct device *dev)
	124	{
	125	const char *tmp = NULL;
	126	struct req req;
	127
	128	if (!thread)
	129	return 0;
	130
3c2670e6	131	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
2780f1ff AV	132	if (!req.name)
	133	return -ENOMEM;
	134
	135	req.mode = 0;
	136	req.dev = dev;
	137
	138	init_completion(&req.done);
	139
	140	spin_lock(&req_lock);
	141	req.next = requests;
	142	requests = &req;
	143	spin_unlock(&req_lock);
	144
	145	wake_up_process(thread);
	146	wait_for_completion(&req.done);
	147
	148	kfree(tmp);
	149	return req.err;
	150	}
	151
fbd48a69	152	static int dev_mkdir(const char *name, umode_t mode)
2b2af54a	153	{
2b2af54a	154	struct dentry *dentry;
69753a0f	155	struct path path;
2b2af54a KS	156	int err;
2b2af54a KS	157
1ac12b4b	158	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
69753a0f AV	159	if (IS_ERR(dentry))
	160	return PTR_ERR(dentry);
	161
75c3cfa8	162	err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
69753a0f AV	163	if (!err)
69753a0f AV	164	/* mark as kernel-created inode */
75c3cfa8	165	d_inode(dentry)->i_private = &thread;
921a1650	166	done_path_create(&path, dentry);
2b2af54a KS	167	return err;
	168	}
	169
	170	static int create_path(const char *nodepath)
	171	{
5da4e689 AV	172	char *path;
5da4e689 AV	173	char *s;
9d108d25	174	int err = 0;
2b2af54a	175
5da4e689 AV	176	/* parent directories do not exist, create them */
	177	path = kstrdup(nodepath, GFP_KERNEL);
	178	if (!path)
	179	return -ENOMEM;
	180
	181	s = path;
	182	for (;;) {
	183	s = strchr(s, '/');
	184	if (!s)
	185	break;
	186	s[0] = '\0';
	187	err = dev_mkdir(path, 0755);
	188	if (err && err != -EEXIST)
	189	break;
	190	s[0] = '/';
	191	s++;
2b2af54a	192	}
5da4e689	193	kfree(path);
2b2af54a KS	194	return err;
	195	}
	196
4e4098a3 GKH	197	static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
4e4098a3 GKH	198	kgid_t gid, struct device *dev)
2b2af54a	199	{
2b2af54a	200	struct dentry *dentry;
69753a0f	201	struct path path;
2b2af54a KS	202	int err;
2b2af54a KS	203
69753a0f AV	204	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
69753a0f AV	205	if (dentry == ERR_PTR(-ENOENT)) {
2b2af54a	206	create_path(nodename);
69753a0f	207	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
2b2af54a	208	}
69753a0f AV	209	if (IS_ERR(dentry))
	210	return PTR_ERR(dentry);
	211
75c3cfa8	212	err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
69753a0f AV	213	if (!err) {
	214	struct iattr newattrs;
	215
69753a0f	216	newattrs.ia_mode = mode;
4e4098a3 GKH	217	newattrs.ia_uid = uid;
4e4098a3 GKH	218	newattrs.ia_gid = gid;
3c2670e6	219	newattrs.ia_valid = ATTR_MODE\|ATTR_UID\|ATTR_GID;
5955102c	220	inode_lock(d_inode(dentry));
27ac0ffe	221	notify_change(dentry, &newattrs, NULL);
5955102c	222	inode_unlock(d_inode(dentry));
69753a0f AV	223
69753a0f AV	224	/* mark as kernel-created inode */
75c3cfa8	225	d_inode(dentry)->i_private = &thread;
2b2af54a	226	}
921a1650	227	done_path_create(&path, dentry);
2b2af54a KS	228	return err;
	229	}
	230
	231	static int dev_rmdir(const char *name)
	232	{
79714f72	233	struct path parent;
2b2af54a KS	234	struct dentry *dentry;
	235	int err;
	236
79714f72 AV	237	dentry = kern_path_locked(name, &parent);
	238	if (IS_ERR(dentry))
	239	return PTR_ERR(dentry);
75c3cfa8 DH	240	if (d_really_is_positive(dentry)) {
	241	if (d_inode(dentry)->i_private == &thread)
	242	err = vfs_rmdir(d_inode(parent.dentry), dentry);
79714f72 AV	243	else
79714f72 AV	244	err = -EPERM;
2b2af54a	245	} else {
79714f72	246	err = -ENOENT;
2b2af54a	247	}
79714f72	248	dput(dentry);
5955102c	249	inode_unlock(d_inode(parent.dentry));
79714f72	250	path_put(&parent);
2b2af54a KS	251	return err;
	252	}
	253
	254	static int delete_path(const char *nodepath)
	255	{
be6b1dfe	256	char *path;
2b2af54a KS	257	int err = 0;
	258
	259	path = kstrdup(nodepath, GFP_KERNEL);
	260	if (!path)
	261	return -ENOMEM;
	262
ed413ae6	263	for (;;) {
2b2af54a KS	264	char *base;
	265
	266	base = strrchr(path, '/');
	267	if (!base)
	268	break;
	269	base[0] = '\0';
	270	err = dev_rmdir(path);
	271	if (err)
	272	break;
	273	}
	274
	275	kfree(path);
	276	return err;
	277	}
	278
	279	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	280	{
	281	/* did we create it */
2780f1ff	282	if (inode->i_private != &thread)
2b2af54a KS	283	return 0;
	284
	285	/* does the dev_t match */
	286	if (is_blockdev(dev)) {
	287	if (!S_ISBLK(stat->mode))
	288	return 0;
	289	} else {
	290	if (!S_ISCHR(stat->mode))
	291	return 0;
	292	}
	293	if (stat->rdev != dev->devt)
	294	return 0;
	295
	296	/* ours */
	297	return 1;
	298	}
	299
2780f1ff	300	static int handle_remove(const char nodename, struct device dev)
2b2af54a	301	{
79714f72	302	struct path parent;
2b2af54a	303	struct dentry *dentry;
fbde7c61	304	int deleted = 0;
2b2af54a KS	305	int err;
2b2af54a KS	306
79714f72 AV	307	dentry = kern_path_locked(nodename, &parent);
	308	if (IS_ERR(dentry))
	309	return PTR_ERR(dentry);
	310
75c3cfa8	311	if (d_really_is_positive(dentry)) {
79714f72	312	struct kstat stat;
3dadecce	313	struct path p = {.mnt = parent.mnt, .dentry = dentry};
a528d35e DH	314	err = vfs_getattr(&p, &stat, STATX_TYPE \| STATX_MODE,
a528d35e DH	315	AT_STATX_SYNC_AS_STAT);
75c3cfa8	316	if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
79714f72 AV	317	struct iattr newattrs;
	318	/*
	319	* before unlinking this node, reset permissions
	320	* of possible references like hardlinks
	321	*/
91fa2cca EB	322	newattrs.ia_uid = GLOBAL_ROOT_UID;
91fa2cca EB	323	newattrs.ia_gid = GLOBAL_ROOT_GID;
79714f72 AV	324	newattrs.ia_mode = stat.mode & ~0777;
	325	newattrs.ia_valid =
	326	ATTR_UID\|ATTR_GID\|ATTR_MODE;
5955102c	327	inode_lock(d_inode(dentry));
27ac0ffe	328	notify_change(dentry, &newattrs, NULL);
5955102c	329	inode_unlock(d_inode(dentry));
75c3cfa8	330	err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
79714f72 AV	331	if (!err \|\| err == -ENOENT)
79714f72 AV	332	deleted = 1;
2b2af54a	333	}
2b2af54a	334	} else {
79714f72	335	err = -ENOENT;
2b2af54a	336	}
79714f72	337	dput(dentry);
5955102c	338	inode_unlock(d_inode(parent.dentry));
2b2af54a	339
79714f72	340	path_put(&parent);
2b2af54a KS	341	if (deleted && strchr(nodename, '/'))
2b2af54a KS	342	delete_path(nodename);
2b2af54a KS	343	return err;
	344	}
	345
	346	/*
	347	* If configured, or requested by the commandline, devtmpfs will be
	348	* auto-mounted after the kernel mounted the root filesystem.
	349	*/
073120cc	350	int devtmpfs_mount(const char *mntdir)
2b2af54a	351	{
2b2af54a KS	352	int err;
2b2af54a KS	353
fc14f2fe	354	if (!mount_dev)
2b2af54a KS	355	return 0;
2b2af54a KS	356
2780f1ff	357	if (!thread)
2b2af54a KS	358	return 0;
2b2af54a KS	359
312db1aa DB	360	err = ksys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT,
312db1aa DB	361	NULL);
2b2af54a KS	362	if (err)
	363	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	364	else
	365	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	366	return err;
	367	}
	368
f9e0b159	369	static DECLARE_COMPLETION(setup_done);
2780f1ff	370
4e4098a3	371	static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
3c2670e6	372	struct device *dev)
2780f1ff AV	373	{
2780f1ff AV	374	if (mode)
3c2670e6	375	return handle_create(name, mode, uid, gid, dev);
2780f1ff AV	376	else
	377	return handle_remove(name, dev);
	378	}
	379
	380	static int devtmpfsd(void *p)
	381	{
	382	char options[] = "mode=0755";
	383	int *err = p;
9b32105e	384	*err = ksys_unshare(CLONE_NEWNS);
2780f1ff AV	385	if (*err)
2780f1ff AV	386	goto out;
312db1aa	387	*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
2780f1ff AV	388	if (*err)
2780f1ff AV	389	goto out;
447016e9	390	ksys_chdir("/.."); /* will traverse into overmounted root */
a16fe33a	391	ksys_chroot(".");
2780f1ff AV	392	complete(&setup_done);
	393	while (1) {
	394	spin_lock(&req_lock);
	395	while (requests) {
	396	struct req *req = requests;
	397	requests = NULL;
	398	spin_unlock(&req_lock);
	399	while (req) {
e13889ba	400	struct req *next = req->next;
3c2670e6 KS	401	req->err = handle(req->name, req->mode,
3c2670e6 KS	402	req->uid, req->gid, req->dev);
2780f1ff	403	complete(&req->done);
e13889ba	404	req = next;
2780f1ff AV	405	}
	406	spin_lock(&req_lock);
	407	}
65e6757b	408	__set_current_state(TASK_INTERRUPTIBLE);
2780f1ff AV	409	spin_unlock(&req_lock);
2780f1ff AV	410	schedule();
2780f1ff AV	411	}
	412	return 0;
	413	out:
	414	complete(&setup_done);
	415	return *err;
	416	}
	417
2b2af54a KS	418	/*
	419	* Create devtmpfs instance, driver-core devices will add their device
	420	* nodes here.
	421	*/
	422	int __init devtmpfs_init(void)
	423	{
2780f1ff	424	int err = register_filesystem(&dev_fs_type);
2b2af54a KS	425	if (err) {
	426	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	427	"type %i\n", err);
	428	return err;
	429	}
	430
2780f1ff AV	431	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	432	if (!IS_ERR(thread)) {
	433	wait_for_completion(&setup_done);
	434	} else {
	435	err = PTR_ERR(thread);
	436	thread = NULL;
	437	}
	438
	439	if (err) {
2b2af54a KS	440	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
	441	unregister_filesystem(&dev_fs_type);
	442	return err;
	443	}
2b2af54a KS	444
	445	printk(KERN_INFO "devtmpfs: initialized\n");
	446	return 0;
	447	}